The effect of soil fungicides and fumigants on the growth of subterranean clover on new light land.

Summary A SUBTERRANEAN clover establishment difficulty is described, which occurs on new scrubplain soils in Western Australia, and is caused by a widespread seedling mortality, associated with faulty nodulation. During an exploratory investigation conducted on a problem lateritic podsolic soil at Wongan Hills Research Station, the following preliminary results were obtained:— 1. In unsterilised soil very poor establishment of subterranean clover was obtained due to faulty nodulation and heavy losses from seedling mortality. 2. In soil sterilised with vapam and formaldehyde fumigants before planting an excellent stand of well-nodulated plants developed. 3. Partial soil sterilisation resulting from the use of certain fertiliser-fungicide mixtures also promoted good establishment with adequate nodulation. 4. It is concluded that seedling mortality of subterranean clover, as it occurs in this area, is caused by indigenous soil micro-organisms which prevent nodulatio